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Topic: Frequencies for low-power devices around the World (Read 4685 times)

Hi, Here are some regulations regarding unlicensed bands that I've found on Internet. Could you please confirmt that it is valid. Also, correct me please if I am wrong, using 100mW transmitter like rfm69hw does not require to use FHSS.

902-928 MHz is the main frequency band in the US The 260-470 MHz range is also available, but with more limitationsThe 902-928 MHz band is covered by FCC CFR 47, part 15Sharing of the bandwidth is done in the same way as for 2.4 GHz: Higher output power is allowed if you spread your transmitted power and dontoccupy one channel all the timeFCC CFR 47 part 15.247 covers widebandmodulation Frequency Hopping Spread Spectrum (FHSS) with ≥50 channels are allowedup to 1 W, FHSS with 25-49 channels up to 0.25 W Direct Sequence Spread Spectrum (DSSS) and other digital modulationformats with bandwidth above 500 kHz are allowed up to 1WFCC CFR 47 part 15.249 Single channel systems can only transmit with ~0.75 mW output power

Transmitters for non-specific applicationsItem From To Power Comments--------------------------------------------------------------------------------19 433.05 - 434.79 25mW All transmitters20 915  928 3mW All transmitters

Frequency hopping, WiFi and RLAN transmittersItem From To Power Comments--------------------------------------------------------------------------------54 915 - 928 1W A minimum of 20 hopping frequencies must be used55 2400 - 2483.5 500mW A minimum of 15 hopping frequencies must be used56 2400 - 2483.5 4W A minimum of 75 hopping frequencies must be used57 5725 - 5850 4W A minimum of 75 hopping frequencies must be used

The output power is stated as EIRP and is the power coming out of the antenna.

These bands are what most people refer to as the ISM (Industrial Scientific and Medical) bands; you don't need to obtain an official transmitter licence (as long as you stay within the regulations) but also can't expect to be free from interference from other devices. With ISM it will also be difficult to legally defend your position that you are entitled to unobstructed use of these frequencies. A sort of 'First come first served' applies.

Item(s) 55, 56, 57, 59 and 60 may not be of immediate use to everyone but it shows what else is available in common 2.4GHz and 5.8GHz bands.

For the RFM69 and friends the 433MHz and 915MHz items apply (items 19, 20, 54 and 58). Therefore, of the available frequencies for the RFM69/12 modules (433/868/915) only the 433MHz and 915MHz modules may be legally used in Australia.

The modulation type that the RFM69/12 modules use is FSK (Frequency Shift Keying) and is considered 'Digital Modulation'. Therefore under item 58 (using 915MHz) a total power of 1W (30dBm) EIRP is the maximum allowed. In practical terms, a 100mW (20dBm) transmitter may be connected to an antenna with 10dB gain (e.g. 6-element Yagi) and still be within the licence conditions.

What I am unable to verify is the exact specification of the RFM69/12 915MHz modules and their spectral density and bandwidth. If for whatever reason these devices do not comply with the regulations of Item 58 then instead Item 20 applies and the total power out of the antenna must not exceed 3mW. If you cannot regulate the power output of the device through software registers to be that low then an in-line attenuator can be used.

Using the radio's in the ISM band for 433MHz (Item 19) may 'only' allow you to use 25mW but this can be enough for short distance comms (maybe around 20 meters line of sight or so). Also remember that lower frequencies have a higher level of penetration through building structures and vegetation.

For those that have their Australian Amateur Radio Licence, 433MHz may be of more interest as it will allow you up to 30W of output power from the transmitter on that band. Also, there is no Amateur Radio band on 915MHz so the limit is 1W in any case.

I'm glad Artyum started this thread as I have been looking for a single page where all ISM bands per country are mentioned but I could never find one.

When I first started looking at doing things with the RFM12B I was really confused about how the regulations apply but it's getting clearer now. Hopefully this page will turn into the go-to reference for those wanting to know what power levels they can legally operate at.

Thanks for all the products and services you provide Felix, much appreciated!

Did you read the notices on page 6;Note 2 (918-926) if you or another in this range , Where is 433?In accordance with the requirements of footnote AUS 32 and footnote 150 to the Table of Frequency Band Allocations in the Australian Radiofrequency Spectrum Plan 2013, a low interference potential device will not be afforded protection from interference that may be caused by industrial, scientific and medical (ISM) applications in the ISM bands 13.553 MHz  13.567 MHz, 26.957 MHz  27.283 MHz, 40.66 MHz  40.70 MHz, 918 MHz  926 MHz, 2 400 MHz  2 500 MHz, 5 725 MHz  5 875 MHz and 24 000 MHz  24 250 MHz.

Note 4!The operation of a device with an external antenna, other than an antenna supplied with the device, may result in a breach of the conditions of this Class Licence. An external antenna is a removable antenna that is not an integral antenna. An integral antenna is an antenna that is permanently fixed to a device, or which is intended for direct attachment to a fixed connector on the device, without the use of an external cable.

I believe that there are antennae available with reverse threads (they screw the wrong way) specifically to stop the possibility of putting standard antennae on devices that may have a different gain and therefore violate FCC regulations. Initially there were also reverse polarity connectors for the same reason, but in 2000 the FCC deemed those to be widely available, but you can still see some manufacturers using them:www.heilind.com/marketing/documents/cinch_reverse_thread_sma.pdfMark.

After a reply in correspondence to the ACMA here Note 4 means an antenna that can not be plugged or unplugged for quick removal & fixed means it can be bolted where an sma plugs connector is a nut and not a plug like an rca plug.

If in note 2 a person makes a formal complaint that 433 is affecting them in some real way i.e. medically, financially or device interference, someone will be visiting you. All complaints must be investigated.

So it seems that in Australia that at 1W EIRP the only true choice is 918-926Mhz.

Regardless of who uses this bandwidth & first implemented has no bearing , then any interference must be solved between the operators, it is not a concern of the regulatory body.